JP3012066B2 - Extremely anisotropically oriented magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polar anisotropically oriented magnet suitable for use as a permanent magnet type rotor for a motor, a stator, and the like, and more particularly to an improvement in a surface magnetic field in a substantial working area of a working surface. This is advantageous for improving the torque of the motor.

[0002]

2. Description of the Related Art Conventionally, as a cylindrical or columnar permanent magnet for a motor, an isotropic magnet in which magnetic easy axes of magnetic particles do not appear or have a random arrangement, and an easy axis of magnetic particles have A radially anisotropic magnet oriented in the (radial direction), and a polar anisotropic oriented magnet oriented in a very anisotropic manner with a peripheral surface serving as an active surface are known.

[0003]

Among the above-mentioned magnets, the polar anisotropic magnet has the highest magnetic flux density on the working surface and has the best magnetic properties. However, even when such a polar anisotropic magnet is incorporated in an actual motor and used for a stator, for example, the substantial working area contributing to the rotation of the rotor is located at the center in the height direction of the magnet. However, since the end faces the exciting coil and the brush arranged in the motor, it does not contribute to the actual magnetic flux density for rotating the rotor. Therefore, the orientation of such an end is useless.

[0004] The present invention advantageously solves the above-mentioned problem, and effectively improves the surface magnetic field in the actual working area of the working surface by effectively utilizing the magnet orientation at the end in the height direction of the magnet. It is an object of the present invention to propose a polar anisotropically oriented magnet capable of improving the motor torque.

[0005]

Means for Solving the Problems By modifying the magnetic circuit of the molding die and controlling the orientation direction of the magnetic powder particles in the magnet material, the surface magnetic field on the substantial working surface of the extremely anisotropically oriented magnet is controlled. The gist of the present invention which aims to improve is as follows.

[0006] In a magnet having a cylindrical or columnar shape and having an axis of easy magnetization of magnetic powder in a very anisotropic orientation in a cross section orthogonal to the central axis so that one of the peripheral surfaces is used as a working surface, However, in a cross section including the central axis, a polar anisotropically oriented magnet that is focused and oriented toward the center of the working surface.

FIGS. 1 to 3 show a polar anisotropically oriented magnet according to the present invention in a cross section including a perspective view and a central axis as an example of 10 poles orientation. In the drawings, the orientation direction of magnetic powder is shown by a solid line. FIG. 1 shows a cylindrical pole anisotropically oriented magnet having an outer peripheral surface as a working surface.
Is a cylindrical pole anisotropically oriented magnet having an inner circumferential surface as a working surface, and FIG. 3 is a cylindrical pole anisotropically oriented magnet having a circumferential surface as a working surface. On the other hand, a conventional (cylindrical) polar anisotropically oriented magnet is shown in FIG. 4 for comparison. As is clear from the comparison between FIGS. 1 to 3 and FIG. 4, in each of these magnets, in the section including the central axis, the axis of easy magnetization of the magnetic powder is focused toward the center of the working surface.

[0008]

FIG. 5 shows a cross section of a motor using a polar anisotropically oriented magnet for a stator, comparing the magnet of the present invention (FIG. 5A) with a conventional magnet (FIG. 5B). In the figures, 1a and 1b are cylindrical magnets, 2 is a motor case, 3 is a rotor magnetic pole, 4 is a rotor excitation coil, 5 is a rotor shaft, 6 is a brush, 7 is a lead wire for conducting to the brush, and 8 is a rotor shaft. The bearing, 9 is a leaf spring, and 10 is a washer.

As described above, in the conventional magnet (see FIG. 5 (b)), the actual working area facing the rotor is near the center of the magnet, and the end is formed by an exciting coil or the like disposed in the motor. Just facing the brush generates a useless magnetic flux. On the other hand, in the present invention, as shown in FIG. 5 (a), in the section including the central axis of the extremely anisotropically oriented magnet, the orientation direction of the axis of easy magnetization of the magnetic powder is shifted toward the center of the working surface (actual working area). By focusing, substantially all of the magnetic flux is focused on the actual working area, so that the surface magnetic field in the actual working area can be substantially improved by effectively utilizing the orientation of the magnetic particles at the ends, and thus the torque can be reduced. A large motor can be obtained.

As the magnet material of the present invention, both sintered magnets and synthetic resin magnets can be used. Synthetic resin magnets do not sinter at high temperatures unlike sintered magnets, so there is no distortion in the magnet product, and the presence of the binder reduces the rate of cracking and chipping of the magnet product, enabling high-yield production. This is advantageous in that it can be integrally formed with the cup or the cup.

As the magnetic powder for the sintered magnet and the synthetic resin magnet, any of magnetic powders such as ferrite, alnico, samarium-cobalt, and neodymium-iron-boron can be used. Also, the average particle size of the magnetic powder particles can be used within a known range.
For example, 1.5μm for ferrite, 10 ~
50 μm is common.

Conventional synthetic resins can also be used. For example, polyamide-based synthetic resins such as polyamide 12 and polyamide 6, polyvinyl chloride, vinyl acetate copolymer thereof, homo- or copolymerized vinyl-based synthetic resins such as MMA, PS, PPS, PE, PP, and urethane,
Silicone, polycarbonate, PBT, PET, PE
EK, CPE, Hypalon, Neoprene, SBR, NB
A synthetic resin such as R or a thermosetting synthetic resin such as an epoxy-based or phenol-based resin can be used.

Further, the mixing ratio of the magnetic powder and the synthetic resin as a binder depends on the use, but generally the magnetic powder is 40 to 70 v.
ol% is desirable. In addition, it goes without saying that appropriate amounts of conventionally used plasticizers, lubricants, antioxidants, surface treatment agents and the like can be used according to the purpose.

Next, a magnetic circuit device for a magnetic field orientation molding die according to the present invention will be described. FIG. 6 corresponds to a case of manufacturing the cylindrical pole anisotropically oriented magnet in which the outer peripheral surface shown in FIG. 1 is the working surface. FIG. 6 (a) shows a cross section including the central axis, and FIG. (b) and (c) show the AA cross section and BB in FIG.
3 shows a cross section. Number 11a in the figure is a cylindrical cavity,
In the cavity 11a, the central region of the outer peripheral surface is a ring magnet 12 for extremely anisotropic orientation, the end of the outer peripheral surface is a non-magnetic material 15, the inner peripheral surface is a non-magnetic material 13, and both end surfaces are ferromagnetic materials. At 14, each is formed to surround. More preferably, the vicinity of both ends of the inner peripheral surface is made of a non-magnetic material.

As described above, the ring magnet 12 for polar anisotropic orientation is
It is characterized in that it has a length shorter than the total height of the magnet to be formed, is located in the central area of the working surface of the magnet, and has the ferromagnetic material 14 on both end faces.

As shown in FIG. 6, the synthetic resin magnet material introduced into the cylindrical cavity 11a by, for example, injection molding is subjected to a magnetic field from the annular magnet 12 disposed on the outer peripheral surface during the softening state. At the end of the cavity, the lines of magnetic force are attracted to the ferromagnetic material 14, and the direction of the arrow shown in the drawing (the direction of the arrow does not matter) is applied. The orientation of the magnetic particles results in the formation of a focused orientation at the working surface.

Incidentally, also in the case of a columnar pole anisotropic magnet, the pole anisotropic orientation of the present invention can be imparted by applying the magnetic circuit device shown in FIG. In this case, the non-magnetic body 13 is unnecessary.

Next, the magnetic circuit device shown in FIG. 7 corresponds to the case of manufacturing the cylindrical pole anisotropically oriented magnet having the inner peripheral surface shown in FIG. 2 as the working surface, and FIG. The cross section including the central axis is shown, and (b) and (c) in FIG.
BB section is shown. In the figure, reference numeral 11b denotes a cylindrical cavity. This cavity 11b is a central region (actual working region) of the inner peripheral surface. An annular magnet 17 for polar anisotropic orientation. The outer peripheral surface is surrounded by a non-magnetic material 19, and both end surfaces are surrounded by a ferromagnetic material 20, respectively. More preferably, the vicinity of both ends of the outer peripheral surface is made of a non-magnetic material. Reference numeral 18 denotes a back yoke (ferromagnetic material).

As described above, the ring magnet 17 for polar anisotropic orientation is
A magnet shorter than the total height of the magnet to be made (length equal to the actual working area of the magnet working face) is arranged in the center area of the working face of the magnet to be made, and ferromagnetic bodies 20 are arranged on both end faces. It is characteristic. Now, as shown in FIG. 7, the synthetic resin magnet material introduced into the cylindrical cavity 11b by, for example, injection molding applies a magnetic field from the annular magnet 17 disposed on the inner peripheral surface while in the softened state. At this time, the magnetic force lines are drawn to the ferromagnetic material 20 at the end of the cavity, and the magnetic particles are oriented in the direction indicated by the arrow in the drawing (the direction of the arrow does not matter). And consequently a focused orientation at the working surface is formed.

The materials of the ferromagnetic bodies 14 and 20 are as follows:
Carbon steel such as S55C, S50C, and S40C, die steel such as SKD11 and SKD61, permendur, and pure iron are used. It is more advantageous to perform a surface hardening treatment for improving abrasion resistance. The material of the non-magnetic materials 13, 15, 19 and 21 is SUS 30
For example, austenitic stainless steel such as No. 4, high manganese steel such as YHD50, copper beryllium alloy, bronze, brass and non-magnetic cemented carbide N-7 are used.

Known magnets can be used for the ring magnets 12 and 17. For example, a permanent magnet such as a samarium-cobalt magnet, or an electromagnet in which an exciting coil is made of a ferromagnetic material can be used.

As the molding method in a magnetic field, known molding methods can be used, and examples thereof include magnetic field orientation injection molding, magnetic field orientation compression molding, and magnetic field orientation RIM molding.

When a rare earth magnetic powder is used, it is desirable to apply a pulsed high magnetic field in advance or immediately after the rare earth magnetic powder has been introduced, and to perform a pretreatment for equalizing the magnetic moment.

FIG. 8 shows an example in which a synthetic resin magnet is integrally formed with a shaft or a cup.

[0025]

EXAMPLE Using a mold magnetic circuit shown in FIG. 7, a cylindrical pole anisotropically oriented magnet having an inner peripheral surface as a working surface shown in FIG. 9 was produced by a magnetic field orientation injection molding method and a magnetic field orientation compression molding method. .
The inner diameter of the magnet of FIG. 9 is 26 mm, the outer diameter is 36 mm, the height is 32 mm, and the length of the actual working area of the inner peripheral surface is 24 mm.

The following two types of magnetic powder were used. Magnetic powder A: Ferrite magnetic powder (magnet plumbite-based strontium-based ferrite having an average particle size of 1.5 μm) Magnetic powder B: Samarium-cobalt magnetic powder (Sm ₂ Co _17- based, average particle size of 15 μm)

The raw materials for the magnets were one type each of a synthetic resin magnet and a sintered magnet. Compound A (compound of synthetic resin magnet) Magnetic powder: 63 vol%, Polyamide 12: 36 vol%, Aminosilane A-1100: 1 vol% Compound B (compound of sintered magnet) Magnetic powder: 50 wt%, water 50 wt%

The molding conditions were one type of synthetic resin magnet and one sintered magnet, respectively. Molding condition A (synthetic resin magnet) Pellet blending used: blending A Molding machine: Built-in coil type magnetic field injection molding machine Injection cylinder temperature: 300 ° C Mold temperature: 100 ° C Injection pressure: 1500kgf / cm ² Excitation time for orientation: 15 Second Cooling time: 20 seconds Injection cycle: 40 seconds Molding condition B (sintered magnet) Slurry: Blending B Molding machine: Magnetic coil oriented compression molding machine with coil Drainage method: Injection method Excitation direction: Vertical magnetic field Molding temperature: 20 ℃ Firing temperature ： 1250 ℃

Table 1 shows the measurement results of the thus obtained surface magnetic flux density on the working surface of the magnet and the motor holding torque value when the magnet is incorporated in a motor as a stator. For comparison, the measurement results of a conventional extremely anisotropically oriented magnet in which the magnetic powder is not focused and oriented on the working surface in a section including the central axis are also shown. The surface magnetic flux density is 70
It was measured by a Gauss meter using a Hall element made of gallium arsenide of μm square, and the motor holding torque was incorporated in the DC motor shown in FIG. 5 and shown by relative evaluation based on a comparative example.

[0030]

[Table 1]

As is clear from the table, in Examples 1 to 4 in which the magnetic powder particles in the cylindrical magnet were focused and oriented in the central region of the working surface according to the present invention, the surface magnetic field on the working surface was improved.
The motor torque has also improved accordingly.

[0032]

According to the pole-anisotropically oriented magnet of the present invention, since the axis of easy magnetization of the magnetic powder is focused and oriented toward the center of the working surface in a cross section including the central axis, the substantial effect of the working surface is achieved. The surface magnetic field in the region can be improved, and the torque can be advantageously improved when incorporated in the motor.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a cylindrical pole anisotropically oriented magnet having an outer peripheral surface as a working surface according to the present invention.

FIG. 2 is an explanatory diagram of a cylindrical pole anisotropically oriented magnet having an inner peripheral surface as a working surface according to the present invention.

FIG. 3 is an explanatory view of a cylindrical pole anisotropically oriented magnet having a peripheral surface as a working surface according to the present invention.

FIG. 4 is an explanatory view of a conventional polar anisotropically oriented magnet.

FIG. 5 is a cross-sectional view of a motor using a polar anisotropically oriented magnet for a stator.

FIG. 6 is an explanatory view of a magnetic circuit device of a magnetic field orientation molding die of a cylindrical pole anisotropically oriented magnet whose outer peripheral surface corresponding to FIG. 1 is an action surface.

FIG. 7 is an explanatory view of a magnetic circuit device of a magnetic field orientation molding die of a cylindrical pole anisotropically oriented magnet whose inner peripheral surface corresponds to FIG.

FIG. 8 is an explanatory diagram of a synthetic resin magnet formed integrally with a shaft and a cup.

FIG. 9 is an explanatory diagram of the dimensions and shape of the magnet used in the example.

Continuing from the front page (72) Inventor Takahiro Kikuchi 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Corp. Technology Research Division (72) Inventor Akira Yasuda 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Kawasaki Steel Corporation Tokyo Head Office (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01F 7/02

Claims (1)

(57) [Claims] 1. A magnet having a cylindrical or columnar shape, wherein an axis of easy magnetization of magnetic powder is aligned in a very anisotropic orientation in a cross section orthogonal to a central axis so that one of the peripheral surfaces is used as a working surface. A polar anisotropically oriented magnet whose easy axis is focused toward the center of the working surface in a cross section including the central axis.